The main |
Parts |
Heat |
Êàðòà íîìîãðàìì |
Ñïðàâî÷íàÿ èíôîðìàöèÿ |

Let's work out the equation of thermal balance:

**L · P · a · dT _{n} = G · C_{p} · (T_{out}-T_{in}),
[1]**

where

**a** – convective heat exchange coefficient, W/(m^{2}·Ê);

**L** – length of a heated up site of the pipeline, m;

**P** – perimetre of a flow section of the pipeline, m;

**dT _{n}** – temperature pressure, Ê;

**T _{in}, T_{out} ** – Fluid temperature on an inlet and an exit of a heated up site of the pipeline, K;

**G** – The mass rate of flux of a fluid, kg/s;

**C _{p}** – specific heat capacity of a fluid, J/(kg·Ê).

Substituting in (1) expression for an arithmetic-mean temperature head at temperature of wall T_{w}:

**dT _{n} = [T_{out} - T_{in}]/ln[(T_{w}-T_{in}) / (T_{w}-T_{out})],
[2]**

let's gain the formula for definition of length of a section of heating: :

**L = G · C _{p} · ln[(T_{w}-T_{in})/(T_{w}-T_{out})] / (a · P).
[3]**

The circuit design of nomographs is presented in drawing 1.

Drawing 1. The circuit design of system of nomographs

After applet start an auxiliary window will have the following appearance (drawing 2).

Drawing 2. An additional window of an applet on build-up of system of nomographs

In an auxiliary window the circuit design of disposing of nomographs is already shown, but she demands recurring feeding into, therefore on each small square which is marking out a nomograph "is clicked" by the right key of the mouse and the left key "clicked"on that place where there should be a colour flag indicator (a place of disposing of meaning of parametre Z of a nomograph). It is possible choose any other location of variable parametre Z. After recurring appointment of the circuit design of nomographs "is clicked" by the left key of the mouse on sign "[-]", had in left overhead to the angle of the circuit design of nomographs. It will change the aspect on "[+]". It means, that the circuit design of nomographs is fixed. .

Drawing 3. An additional window of an applet on build-up of system of nomographs with the tuned circuit design of nomographs

After attaching of the circuit design of nomographs, "is in succession clicked" on everyone sign, marking out a nomograph, and it is pushed three buttons "In the working memory" ("Â ÎÇÓ"), "Substitution ID" ("Ïîäñòàíîâêà ÈÄ"), "the Total formula" ("Èòîãîâàÿ ôîðìóëà") for entering of all parametres of a nomograph into an on-line storage and design formula formation.

We transfer to the basic window and we induct meanings of steps on axes "X" and "Y". We push the button "to Build on ID" ("Ïîñòðîèòü ïî ÈÄ").

Drawing 4. The basic window of an applet for build-up of system of nomographs.

More detailed instruction on operation with an applet.

graphic-analytical systems

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